kernel/capability.c

   1 /*
   2  * linux/kernel/capability.c
   3  *
   4  * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
   5  *
   6  * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
   7  * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
   8  */
   9
  10 #include <linux/mm.h>
  11 #include <linux/module.h>
  12 #include <linux/security.h>
  13 #include <linux/syscalls.h>
  14 #include <asm/uaccess.h>
  15
  16 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  17 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  18
  19 EXPORT_SYMBOL(securebits);
  20 EXPORT_SYMBOL(cap_bset);
  21
  22 /*
  23  * This lock protects task->cap_* for all tasks including current.
  24  * Locking rule: acquire this prior to tasklist_lock.
  25  */
  26 static DEFINE_SPINLOCK(task_capability_lock);
  27
  28 /*
  29  * For sys_getproccap() and sys_setproccap(), any of the three
  30  * capability set pointers may be NULL -- indicating that that set is
  31  * uninteresting and/or not to be changed.
  32  */
  33
  34 /*
  35  * sys_capget - get the capabilities of a given process.
  36  */
  37 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  38 {
  39      int ret = 0;
  40      pid_t pid;
  41      __u32 version;
  42      task_t *target;
  43      struct __user_cap_data_struct data;
  44
  45      if (get_user(version, &header->version))
  46              return -EFAULT;
  47
  48      if (version != _LINUX_CAPABILITY_VERSION) {
  49              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  50                      return -EFAULT;
  51              return -EINVAL;
  52      }
  53
  54      if (get_user(pid, &header->pid))
  55              return -EFAULT;
  56
  57      if (pid < 0)
  58              return -EINVAL;
  59
  60      spin_lock(&task_capability_lock);
  61      read_lock(&tasklist_lock);
  62
  63      if (pid && pid != current->pid) {
  64              target = find_task_by_pid(pid);
  65              if (!target) {
  66                   ret = -ESRCH;
  67                   goto out;
  68              }
  69      } else
  70              target = current;
  71
  72      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  73
  74 out:
  75      read_unlock(&tasklist_lock);
  76      spin_unlock(&task_capability_lock);
  77
  78      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  79           return -EFAULT;
  80
  81      return ret;
  82 }
  83
  84 /*
  85  * cap_set_pg - set capabilities for all processes in a given process
  86  * group.  We call this holding task_capability_lock and tasklist_lock.
  87  */
  88 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  89                               kernel_cap_t *inheritable,
  90                               kernel_cap_t *permitted)
  91 {
  92         task_t *g, *target;
  93         int ret = -EPERM;
  94         int found = 0;
  95
  96         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
  97                 target = g;
  98                 while_each_thread(g, target) {
  99                         if (!security_capset_check(target, effective,
 100                                                         inheritable,
 101                                                         permitted)) {
 102                                 security_capset_set(target, effective,
 103                                                         inheritable,
 104                                                         permitted);
 105                                 ret = 0;
 106                         }
 107                         found = 1;
 108                 }
 109         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 110
 111         if (!found)
 112              ret = 0;
 113         return ret;
 114 }
 115
 116 /*
 117  * cap_set_all - set capabilities for all processes other than init
 118  * and self.  We call this holding task_capability_lock and tasklist_lock.
 119  */
 120 static inline int cap_set_all(kernel_cap_t *effective,
 121                                kernel_cap_t *inheritable,
 122                                kernel_cap_t *permitted)
 123 {
 124      task_t *g, *target;
 125      int ret = -EPERM;
 126      int found = 0;
 127
 128      do_each_thread(g, target) {
 129              if (target == current || target->pid == 1)
 130                      continue;
 131              found = 1;
 132              if (security_capset_check(target, effective, inheritable,
 133                                                 permitted))
 134                      continue;
 135              ret = 0;
 136              security_capset_set(target, effective, inheritable, permitted);
 137      } while_each_thread(g, target);
 138
 139      if (!found)
 140              ret = 0;
 141      return ret;
 142 }
 143
 144 /*
 145  * sys_capset - set capabilities for a given process, all processes, or all
 146  * processes in a given process group.
 147  *
 148  * The restrictions on setting capabilities are specified as:
 149  *
 150  * [pid is for the 'target' task.  'current' is the calling task.]
 151  *
 152  * I: any raised capabilities must be a subset of the (old current) permitted
 153  * P: any raised capabilities must be a subset of the (old current) permitted
 154  * E: must be set to a subset of (new target) permitted
 155  */
 156 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 157 {
 158      kernel_cap_t inheritable, permitted, effective;
 159      __u32 version;
 160      task_t *target;
 161      int ret;
 162      pid_t pid;
 163
 164      if (get_user(version, &header->version))
 165              return -EFAULT;
 166
 167      if (version != _LINUX_CAPABILITY_VERSION) {
 168              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 169                      return -EFAULT;
 170              return -EINVAL;
 171      }
 172
 173      if (get_user(pid, &header->pid))
 174              return -EFAULT;
 175
 176      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 177              return -EPERM;
 178
 179      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 180          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 181          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 182              return -EFAULT;
 183
 184      spin_lock(&task_capability_lock);
 185      read_lock(&tasklist_lock);
 186
 187      if (pid > 0 && pid != current->pid) {
 188           target = find_task_by_pid(pid);
 189           if (!target) {
 190                ret = -ESRCH;
 191                goto out;
 192           }
 193      } else
 194                target = current;
 195
 196      ret = 0;
 197
 198      /* having verified that the proposed changes are legal,
 199            we now put them into effect. */
 200      if (pid < 0) {
 201              if (pid == -1)  /* all procs other than current and init */
 202                      ret = cap_set_all(&effective, &inheritable, &permitted);
 203
 204              else            /* all procs in process group */
 205                      ret = cap_set_pg(-pid, &effective, &inheritable,
 206                                                         &permitted);
 207      } else {
 208              ret = security_capset_check(target, &effective, &inheritable,
 209                                                         &permitted);
 210              if (!ret)
 211                      security_capset_set(target, &effective, &inheritable,
 212                                                         &permitted);
 213      }
 214
 215 out:
 216      read_unlock(&tasklist_lock);
 217      spin_unlock(&task_capability_lock);
 218
 219      return ret;
 220 }